1. Technical Field
The present invention relates to a novel resin composition containing a cyclic monomer unit-containing polymer. More particularly, the present invention is concerned with a novel resin composition comprising (.alpha.) at least one polymer selected from the group consisting of a non-modified cyclic monomer unit-containing polymer and a modified cyclic monomer unit-containing polymer, wherein the cyclic monomer unit is derived from a cyclic conjugated diene, and (.beta.) at least one polymer other than the polymer (.alpha.), which resin composition is excellent in thermal properties, such as thermal stability with respect to rigidity, and mechanical properties, such as impact resistance.
2. Prior Art
In recent years, polymer chemistry has continuously made progress through various innovations in order to meet commercial demands which have been increasingly diversified. Especially in the field of polymer materials to be used as commercially important materials, extensive and intensive studies have been made toward developing polymers having more excellent thermal and mechanical properties. Various proposals have been made with respect to such polymers and methods for the production thereof.
Polymer materials are advantageous in that they have light weight and have a large freedom of selection with respect to the shapes of ultimate molded products, and that a wide variety of unique properties can be exhibited in accordance with the types of polymer materials used. Therefore, polymer materials are used in an extremely wide variety of application fields, such as those for automobile parts, electric and electronic parts, railroad parts, aircraft parts, fibers, clothes, medical equipment parts, packaging materials for drugs and foods and materials for general miscellaneous goods. Further, in accordance with the diversification of commercial demands and the progress of technology, the importance of polymer materials has been increasing by great leaps.
In recent years, due to a rise in the consciousness about environmental problems, with respect to materials to be used in, for example, the fields of automobile parts, electric and electronic parts and the like, a demand for decreasing the number of the types of necessary materials so as to decrease the weight and number of parts, has been rapidly increasing. For the purpose of meeting this demand, energetic researches have been widely conducted on how to replace structural non-polymer materials with polymer materials and how to decrease the number of the types of structural materials.
However, as one of the most important problems which must be solved for developing polymer materials, especially organic polymer materials, which can be widely used as structural materials, there is a problem inherent in conventional polymer materials, namely a problem that polymer materials exhibit a considerably large change in mechanical properties in accordance with changes in ambient temperature.
The reason for the occurrence of the above-mentioned phenomenon with conventional polymer materials is generally presumed to be as follows. When the ambient temperature of a polymer material is elevated to a temperature which is higher than the glass transition temperature (Tg) of the polymer material, the molecular chain of the polymer is changed from a glassy state to a rubbery state, and this change of state becomes a main cause for a considerably larger change in mechanical properties. Therefore, it has, in principle, been impossible to solve this problem insofar as a polymer material having a single molecular structure is used, so that extensive and intensive studies have been made for solving the problem by using a combination of a plurality of different types of polymer materials.
For example, in order to obtain a polymer material having mechanical properties (such as thermal stability with respect to rigidity and mechanical strength, impact resistance and dimensional stability) which are not only improved, but also are unlikely to suffer an unfavorable change at ambient temperatures, it has been attempted to use a polymer material in combination with other polymers, which are different from the polymer material in glass transition temperature (Tg), to obtain composite polymer materials, or to copolymerize a plurality of types of monomers to thereby produce a polymer material comprising a copolymer chain having segments which are different in glass transition temperature.
Examples of such conventional techniques include:
a method in which a polymer, which has a relatively high melting temperature (Tm) but does not have a satisfactorily high Tg such as a polyamide (PA), a polyester (PEs), a polyphenylene sulfide (PPS), a polyacetal (e.g., a polyoxymethylene, that is, POM) or a polypropylene (PP)!, is used in combination with another type of polymer which has a relatively high Tg such as a polyphenylene ether (PPE), a polycarbonate (PC), a polyarylate (PAR), a polysulfone (PSF), a polyether ketone (PEK), a polyether ether ketone (PEEK), a liquid crystal polyester (LCP) or a polystyrene (PSt)!, to thereby obtain a polymer material having an improved thermal stability with respect to rigidity; PA1 a method in which a polymer which does not have a satisfactorily low Tg such as a polyamide (PA), a polyester (PEs), a polyphenylene sulfide (PPS), a polyacetal (e.g., a polyoxymethylene, that is, POM), a polypropylene (PP), a polyphenylene ether (PPE) or a polystyrene (PSt)!, is used in combination with a polymer which has a relatively low Tg such as an ethylene-propylene rubber (EPR), an ethylene-propylene-diene terpolymer (EPDM), a styrene-butadiene rubber (SBR), a hydrogenated styrene-butadiene rubber (styrene-ethylene-butylene-styrene, that is, SEBS), a styrene-isoprene rubber (SIR), a hydrogenated styrene-isoprene rubber, a butadiene rubber (BR), an isoprene rubber (IR), a chloroprene rubber (CR), a nitrile rubber (acrylonitrile-butadiene rubber, that is, NBR), an ethylene-containing ionomer, an acrylic rubber, a silicone rubber, a fluororubber, a polyamide elastomer or a polyester elastomer!, to thereby obtain a polymer material having an improved impact resistance; PA1 a method in which a polymer, such as a polystyrene (PSt), a styrene-butadiene rubber (SBR), a hydrogenated styrene-butadiene rubber (SEBS), a styrene-isoprene rubber (SIR), a hydrogenated styrene-isoprene rubber, ABS resin or AES resin, is used in combination with a polymer having a relatively high Tg, to thereby obtain a polymer material having an improved thermal stability with respect to mechanical strength; and PA1 a method in which an aromatic or aliphatic cyclic monomer unit is introduced, by copolymerization, into the molecular chain of a polymer, such as a polyamide (PA), a polyester (PEs), a polypropylene (PP) or a polyethylene (PE), to thereby obtain a polymer material having an improved thermal stability with respect to rigidity, mechanical strength and the like. Of these known methods, several methods have already been commercially practiced.
However, in these conventional techniques, it is necessary that the respective types of different polymers to be used in combination or the respective types of a monomer and a comonomer to be used in combination be largely varied depending on the properties to be improved. Therefore, these conventional methods are not always in line with the market trend that it is desired to decrease the number of the types of structural materials.
As a solution to this problem, a (hydrogenated) conjugated diene polymer has been proposed. A conjugated diene polymer can be produced by living anionic polymerization, so that a conjugated diene polymer has a large freedom with respect to the designing of the molecular chain and it is relatively easy to control the properties of a conjugated diene polymer to be obtained, for example, by copolymerization. Therefore, it is conceivable that, when a conjugated diene polymer having properties appropriately controlled, e.g., by copolymerization, is used as a modifier for a polymer material, various properties, such as thermal stability with respect to rigidity and mechanical strength, impact strength and dimensional stability, can be imparted to the polymer material with a large freedom. Hence, researches have been intensively conducted for development of conjugated diene polymers as a representative modifier component for composite resin materials.
Representative examples of known conjugated diene polymers include homopolymers, such as a polybutadiene and a polyisoprene; copolymers of block, graft, taper and random configurations, such as a butadiene-isoprene copolymer, a styrene-butadiene copolymer, a propylene-butadiene copolymer, a styrene-isoprene copolymer, an .alpha.-methylstyrene-butadiene copolymer, an .alpha.-methylstyrene-isoprene copolymer, an acrylonitrile-butadiene copolymer, an acrylonitrile-isoprene copolymer, a butadiene-methyl methacrylate copolymer and an isoprene-methyl methacrylate copolymer; and hydrogenated polymers derived therefrom. These polymers have been used for various purposes in various fields. For example, in combination with other polymers, these conventional conjugated diene polymers have been used as plastics; elastomers; fibers; sheets; films; materials for parts for machines, containers for food, packing materials, tires and belts; insulating materials; adhesives; and the like.
For example, in the field of thermoplastic elastomers, when a conjugated diene polymer in the form of a thermoplastic elastomer is used as a modifier for improving the impact resistance of a polymer material, a conjugated diene block copolymer has conventionally been used which comprises a polymer chain composed of an agglomeration phase which is of a polymer block having a Tg (glass transition temperature) higher than room temperature, and an elastomer phase which is of a polymer block having a Tg lower than room temperature.
Representative examples of such block copolymers include a styrene-butadiene (isoprene)-styrene block copolymer and a hydrogenated product thereof.
Further, for improving various properties (such as thermal resistance, fluidity and adhesion properties) of the styrene-butadiene (isoprene)-styrene block copolymer or a hydrogenated product thereof, it has been widely practiced to use the block copolymer or a hydrogenated product thereof in the form of a block copolymer composition which is obtained by blending the above-mentioned block copolymer or a hydrogenated product thereof with another polymer, such as a polystyrene, a polyolefin, a polyphenylene ether or a styrene-butadiene diblock copolymer, or a hydrogenated product thereof.
On the other hand, various proposals have been made with respect to the method for producing a conjugated diene polymer, which is also very important from a commercial point of view.
Particularly, various studies have been made with a view toward developing a polymerization catalyst capable of providing conjugated diene polymers having a high cis-1,4-bond content, for the purpose of obtaining conjugated diene polymers having improved thermal and mechanical properties.
For example, a catalyst system comprised mainly of a compound of an alkali metal, such as lithium or sodium, and a composite catalyst system comprised mainly of a compound of a transition metal, such as nickel, cobalt or titanium, have been proposed. Some of these catalyst systems have already been employed for a commercial scale practice of the polymerization of butadiene,. isoprene and the like (see, for example, Ind. Eng. Chem., 48, 784 (1956) and Examined Japanese Patent Application Publication No. 37-8193).
On the other hand, for not only obtaining a conjugated diene polymer having a further increased cis-1,4-bond content but also providing a catalyst having a further improved polymerization activity, a number of studies have been made toward developing a composite catalyst system comprising a rare earth metal compound and an organometallic compound containing a metal belonging to Group I, II or III of the Periodic Table. Further, in connection with the study of such a catalyst system, intensive studies have also been made with respect to highly stereospecific polymerization see, for example, J. Polym. Sci., Polym. Chem. Ed., 18, 3345 (1980); Sci, Sinica., 2/3, 734 (1980); Makromol. Chem. Suppl, 4, 61 (1981); German Patent Application No. 2,848,964; Rubber Chem. Technol., 58, 117 (1985)!.
Among these composite catalyst systems, a composite catalyst comprised mainly of a neodymium compound and an organoaluminum compound has been confirmed to have not only the ability to provide a desired polymer having a high cis-1,4-bond content, but also exhibits an excellent polymerization activity. Accordingly, this type of composite catalyst has already been commercially used as a catalyst for the polymerization of butadiene or the like see, for example, Agnew, Makromol. Chem., 94, 119 (1981); Macromolecules, 15, 230 (1982)!.
However, in accordance with the recent remarkable progress of the techniques in this field, there has been a strong demand for the development of polymer materials having further improved properties, particularly excellent thermal properties (such as melting temperature, glass transition temperature and heat distortion temperature) and excellent mechanical properties (such as tensile modulus and flexural modulus).
As one of the most practical means for meeting such a demand, it has been attempted to develop a technique of improving the structures of the main molecular chains of polymers of conjugated diene monomers (in homopolymerizing or copolymerizing not only a monomer having a relatively small steric hindrance, e.g., butadiene or isoprene, but also a monomer having a large steric hindrance, e.g., a cyclic conjugated diene monomer, and, optionally, hydrogenating the resultant conjugated diene polymer, thereby forming a cyclic olefin monomer unit in the molecular chain) so as to obtain conjugated diene polymers having excellent thermal properties (such as thermal stability with respect to rigidity and mechanical strength), excellent impact resistance and excellent dimensional stability. Further, it has also been attempted to use these conjugated diene polymers in combination with other polymers so as to obtain composite resin materials having improved properties.
With respect to the homopolymerization or copolymerization of a monomer having a relatively small steric hindrance, e.g., butadiene or isoprene, catalyst systems having a polymerization activity which is satisfactory to a certain extent have been successfully developed. However, a catalyst system which exhibits a satisfactory polymerization activity in the homopolymerization or copolymerization of monomers having a large steric hindrance, e.g., a cyclic conjugated diene monomer, has not yet been developed.
That is, by conventional techniques, even homopolymerization of a cyclic conjugated diene is difficult, so that a homopolymer having a desired high molecular weight cannot be obtained. Furthermore, an attempt to copolymerize a cyclic conjugated diene with a monomer other than the cyclic conjugated diene, for the purpose of obtaining a polymer having optimized thermal and mechanical properties in order to meet a wide variety of commercial needs, has been unsuccessful with the result that the products obtained are only oligomers having a low molecular weight.
Further, the carbon--carbon double bond in a cyclic conjugated diene monomer unit of a conjugated diene polymer has a large steric hindrance. Due to this, in conventional techniques, there is a serious problem in that when it is attempted to introduce a cyclic olefin monomer unit into the molecular chain of a conjugated diene polymer by a hydrogenation reaction, the rate of the hydrogenation reaction is considerably low, so that it is extremely difficult to introduce a cyclic olefin monomer unit into the conjugated diene polymer.
As is apparent from the above, in any of the conventional techniques, it has been impossible to obtain an excellent polymer containing a cyclic conjugated diene monomer unit and/or a cyclic olefin monomer unit, which polymer can satisfy commercial demand. Therefore, it has been strongly desired to develop excellent polymers containing a cyclic monomer unit.
J. Am. Chem. Soc., 81, 448 (1959) discloses a cyclohexadiene homopolymer and a polymerization method therefor, which homopolymer is obtained by polymerizing 1,3-cyclohexadiene (a typical example of a cyclic conjugated diene monomer), using a composite catalyst comprised of titanium tetrachloride and triisobutylaluminum.
However, the polymerization method disclosed in this prior art document is disadvantageous in that the use of a large amount of the catalyst is necessary, and the polymerization reaction must be conducted for a prolonged period of time, and that the obtained polymer has only an extremely low molecular weight. Therefore, the polymer obtained by the technique of this prior art document is of no commercial value.
Further, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
J. Polym. Sci., Pt. A, 2, 3277 (1964) discloses methods for producing a cyclohexadiene homopolymer, in which the polymerization of 1,3-cyclohexadiene is conducted by various polymerization methods, such as radical polymerization, cationic polymerization, anionic polymerization and coordination polymerization.
However, in all of the methods disclosed in this prior art document, the polymers obtained have an extremely low molecular weight. Therefore, the polymers obtained by the techniques of this prior art document are of no commercial value. Further, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the polymeric molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
British Patent Application No. 1,042,625 discloses a method for producing a cyclohexadiene homopolymer, in which the polymerization of 1,3-cyclohexadiene is conducted using a large amount of an organolithium compound as a catalyst.
In the polymerization method disclosed in British Patent Application No. 1,042,625, the catalyst must be used in an amount as large as 1 to 2 wt %, based on the total weight of the monomers. Therefore, this method is economically disadvantageous. Further, the polymer obtained by this method has only an extremely low molecular weight.
Moreover, the method of this prior art document has disadvantages in that the polymer obtained contains a large amount of catalyst residue, which is very difficult to remove from the polymer, so that the polymer obtained by this method is of no commercial value.
Furthermore, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
J. Polym. Sci., Pt. A, 3, 1553 (1965) discloses a cyclohexadiene homopolymer, which is obtained by polymerizing 1,3-cyclohexadiene using an organolithium compound as a catalyst. In this prior art document, the polymerization reaction must be continued for a period as long as 5 weeks, however, the polymer obtained has a number average molecular weight of only 20,000 or less.
Further, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
Polym. Prepr. (Amer. Chem. Soc., Div. Polym. Chem.) 12, 402 (1971) teaches that when the polymerization of 1,3-cyclohexadiene is conducted using an organolithium compound as a catalyst, the upper limit of the number average molecular weight of the cyclohexadiene homopolymer obtained is only from 10,000 to 15,000. Further, this document teaches that the reason for such a small molecular weight resides in that, concurrently with the polymerization reaction, not only does a transfer reaction occur, which is caused by the abstraction of a lithium cation present in the polymer terminal, but also a lithium hydride elimination reaction occurs.
Furthermore, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
Die Makromolekulare Chemie., 163, 13 (1973) discloses a cyclohexadiene homopolymer which is obtained by polymerizing 1,3-cyclohexadiene using a large amount of an organolithium compound as a catalyst. However, the polymer obtained in this prior art document is an oligomer having a number average molecular weight of only 6,500.
Further, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
European Polymer J., 9, 895 (1973) discloses a copolymer which is obtained by copolymerizing 1,3-cyclohexadiene with butadiene and/or isoprene, using a .pi.-allylnickel compound as a polymerization catalyst.
However, the polymer obtained in this prior art document is an oligomer having an extremely low molecular weight. Further, it has been reported that the polymer of this prior art document has a single glass transition temperature, which suggests that the polymer has a random copolymer structure.
Further, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
Kobunshi Ronbun-shu (Collection of theses concerning polymers), Vol. 34, No. 5, 333 (1977) discloses a method for synthesizing an alternating copolymer of 1,3-cyclohexadiene and acrylonitrile using zinc chloride as a polymerization catalyst. However, the alternating copolymer obtained in this prior art document is an oligomer having an extremely low molecular weight.
Further, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
J. Polym. Sci., Polym. Chem. Ed., 20, 901 (1982) discloses a cyclohexadiene homopolymer which is obtained by polymerizing 1,3-cyclohexadiene using an organosodium compound as a catalyst. In this prior art document, the organosodium compound used is sodium naphthalene, and a radical anion derived from sodium naphthalene forms a dianion which functions as a polymerization initiation site.
This means that although the cyclohexadiene homopolymer reported in this document has an apparent number average molecular weight of 38,700, this homopolymer is actually only a combination of two polymeric molecular chains, each having a number average molecular weight of 19,350, which chains respectively extend from the polymerization initiation site in two different directions.
Further, in the polymerization method disclosed in this document, the polymerization reaction needs to be conducted at an extremely low temperature. Therefore, the technique of this prior art document is of no commercial value.
Furthermore, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
Makromol. Chem., 191, 2743 (1990) discloses a method for polymerizing 1,3-cyclohexadiene using a polystyryllithium as a polymerization initiator. In this prior art document, it is described that concurrently with the polymerization reaction, not only a transfer reaction, which is caused by the abstraction of a lithium cation present in the polymer terminal, but also a lithium hydride elimination reaction vigorously occurs. Further, it is reported that even though the polymerization is conducted using a polystyryllithium as a polymerization initiator, a styrene-cyclohexadiene block copolymer cannot be obtained at room temperature, but the product obtained is only a cyclohexadiene homopolymer having a low molecular weight.
Further, neither a block copolymer of cyclohexadiene and a chain conjugated diene monomer, nor a multiblock copolymer which is an at least-tri-block copolymer containing a cyclohexadiene polymer block, nor a radial block copolymer containing a cyclohexadiene polymer block is taught or suggested in this prior art document.
Furthermore, this prior art document has no teaching or suggestion of a method for introducing a cyclic olefin monomer unit into the main molecular chain of a polymer to obtain a new polymer and use of such a new polymer containing a cyclic olefin monomer unit as a component for providing a composite resin material.
As can be easily understood from the above, in any of the conventional techniques, it has been impossible to obtain a polymer containing a monomer unit derived from a cyclic conjugated diene monomer and an excellent resin composition containing such a polymer, which polymer and resin composition can be satisfactorily used as industrial materials.